In the manufacture of glass articles or other materials, it is necessary to fed gobs of molten glass for the manufacture of glass articles.
These glass gobs are obtained from a feeding source which contains molten glass and thus is able to provide a continuous flow of molten glass, which is continuously shear, through of a shear mechanism, into portions called "gobs", which are distributed by a gob distributor mechanism into one or more cavities of individual forming sections of a glassware forming machine.
The know gob distributors of the prior art generally contain one or more movable distribution scoops, each one of which is supported on a vertical shaft. Said scoops are aligned in such manner that they are moved through adequate mechanisms based on gears, so that said mechanisms are controlled by a moving cam, which makes the scoops move together between a glass article forming station and the next station, in a delivery sequence of predetermined glass gobs, so as to achieve the programmed distribution of the gobs of each one of the forming sections of the machine.
As an example of the gob distributor of the previous art, can be cited the one illustrated in the U.S. Pat. No.: 3,597,187, which was granted to Urban P. Trudeau on Aug. 3, 1971, and assigned to the Owens Illinois Co. This gob distributor consists of a pair of curved scoops, supported by vertical shafts which, through adequate gears, are made to move radially through a gear which is supported on a vertical shaft which moves sequentially through an angle of a predetermined path, through a transversal piston rod which contains a cam follower. Said piston rod is supported on a control cam, which in accordance with its profile, makes that the curved scoops be moved radially between one forming station and the next one, so as to deliver the gobs through a series of set fixed channels which are guided towards the molds of each one of the forming stations of the machine. The control cam is made to turn, itself, by a gear and a screw worm, which is coupled to a shaft. Said shaft is made to turn by a synchronous motor which turn the cam at a constant speed, in synchronization with the operation controls, such as for example, the timing drum which controls the diverse operations of each station of the forming machine.
Another type of gob distributor is illustrated by the U.S. Pat. Re. No. 28,759 granted to Wasyl Bystrianyk et al, on Apr. 6, 1976, and assigned to the Emhart Corporation. This patent also describes a molten glass gobs distributor which essentially includes a pair of curved scoops, each one of which is coupled to a toothed gear, which in turn is coupled to a rack, which permits them to move together, simultaneously, and angularly between one and another position of the glass article forming machine. The rack is coupled itself to a shaft, which at its free end is provided with a cam follower, which in turn is moved by another cam follower, which itself is supported on an adequate cam, which in this particular case, is a horizontal cam. The cam is driven by means of a transmission which is connected to a synchronous motor which makes the cam turn synchronously with the operation controls of the diverse forming sections of the glass article forming machine.
The most recent gob distributors of the previous art already eliminate the use of a motorized cam in order to control the movement of the movable scoops of a glass gob distributor, and its place, they use electronic or stepping motors, such as well as, a control electronic system for the same, such as is illustrated by U.S. Pat. No. 4,357,157, which was granted to Luis Cardenas Franco, et al, on Nov. 2, 1982 and assigned to Investigacion FIC Fideicomiso. In this case, the distributor includes a pair of curved scoops placed one behind the other. The front scoop is provided with a ring support, which is itself supported on a shaft, while the back scoop passes through the aforementioned ring and is supported by a second shaft, in order to carry out the rotating movement at predetermined angles. The shaft of the scoops of distribution pass through a common support, and are coupled by means of an adequate coupling to stepping motors, which operate them in a fully independent manner, through the provision of movements which are perfectly measured by the number of pulses which are fed to each one of the motors. In this case, the stepping motors are operated by an electronic control system which synchronizes the delivery movement of the scoops with respect to each one of the sections of the forming machine.
Another gob distributor of the type that uses programmable means is the one illustrated by the U.S. Pat. No. 4,687,502 granted to Robert J. Douglas et al, and assigned to the company Emhart Industries. This distributor includes a variation to the distribution system described by the U.S. Pat. Re. No. 28,759, which was assigned to said company. In accordance with this invention, the principal characteristics of this gob distributor is the utilization of a servomotor which, is a reversible motor using direct current. This motor positions a rack, which controls the angular movement of the curved scoops for gob delivery. The servomotor is controlled by a servo control positioning mechanism, which itself is controlled by a movement profile through the intervention of a computer which can be manually adjusted. This gob distributor may be considered as being manufactured in two sections, a replaceable section which includes a housing which comprises a pair of toothed pinions which are coupled, respectively, to a pair of feeding scoops. Said pinions, themselves, are coupled to the rack, which makes the two scoops move angularly between one and the other position; and a fixed section which contains the servomotor and a driver of lineal to rotatory movement. This driver may be attached to the principal structure of the glass article forming machine.
However, a disadvantage had by the synchronized distributors that use cams as a movable element for carrying out the movement sequence, which is required by the distribution scoops, is that the cams get considerably worn in view of the fact that they are continually undergoing important efforts to move all of the gob distributing mechanism, so that the surface of the cam is subjected to wear that provokes lack of adjustment in the movement of the distribution channels.
Another considerable disadvantage, which appears because of the mechanical controls based on cams, is that there does not exist the possibility of modifying the operation sequence of these diverse sections of the glass article forming machine, unless the cam is changed by another that is totally different and which contains another sequence.
With the arrival of the electronic controls, the control of the movement of the curved scoops may be handled with great safety, and the programming (adjustment) of the angular position can be easily controlled.
However, one of the problems that still remains with the known gob distributors is with respect to their mechanical structure since they are manufactured with a great quantity of mechanical joining pieces such as guide bars, and other additional pieces which increase considerably its size and weight.
In addition to the above, and due to the large quantity of pieces which make up the known gob distributors, there is the disadvantage in that there exists a great wear in all of the pieces. This provokes disarrangement problems (backlash), which cause rough movements at the time the delivery movement is made, and these cannot be easily corrected by the electrical or electronic controls.